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Title
Column is NotNull when applying unique/alternate key -
Description
When applying a unique/alternate key or Primary key to a column in a table, defining it as NOTNULL in the create script, when the table is reverse engineered the column is set to NotNull automatically, and this option is greyed out, without the possibility of being able to change it in Toad Data Modeler.
Is it possible to have the option to turn this off? -
Cause
This limitation is imposed on some database platforms. If a platform allows nullable the option can be enabled in Toad Data Modeler. -
Resolution
RESOLUTION:
Null for Unique/Alternate keys are allowed in some database platforms and TDM allows the setting when working with these platforms.
1. Go to Setting | Options | Model | Physical Model | General tab.
2. Select Allow Null Attributes in Keys.
TDM will still set to not null by default, but the checkbox to set to nullable should be enabled.
STATUS:
Issue fixed in version 3.6. The latest version of Toad Data Modeler can be downloaded at http://support.quest.com/Search/SearchDownloads.aspx -
Defect ID
CR 48139 -
Additional Information
It is not advised that nullable columns be set for multi-column keys. On most database platforms when a multi-column key allows nullable values for some or all of the columns, when the database evaluates each row of data, if any of the columns have nulls for the row, then the constraint simply does not fire. The constraint is only partially being enforced and the user sees no errors or warning. This may lead to duplicate rows that was not intended. But some platforms do allow nullable. Null for Unique keys are allowed in some database platforms and TDM allows the setting when working with certain platforms. Null for Unique key is allowed in SQL 2005 and later, 2000 does not support it. PK nullable is only allowed in Oracle and Access dbs.